The present invention is generally directed to an engine and, more specifically, to a rotary opposed piston engine.
Various rotary engines have been proposed that implement a plurality of piston pairs that operate in concert. For example, U.S. Pat. No. 2,075,654 discloses a rotary engine, whose expansion chamber is sealed with a ring arranged in a slot of a hollow casing body, so as to be capable of sliding on a flange. The ring includes slots through which arms extend and the rings may be secured to one of the arms. At least one embodiment discloses three working chambers or spaces, which are connected mechanically with one another by three arms secured on a shaft and three planet wheels, which control movement of a corresponding piston.
U.S. Pat. No. 1,950,228 discloses a rotary internal combustion engine that includes a main body having the form of a hollow torus, which includes a plurality of pistons that are connected to a drive shaft, which is located coaxially with the torus. The engine includes a set of cams adapted to periodically increase the periphery speed of each piston, with reference to an adjacent piston, in order to effect a compression in the chamber in the front and a suction in the chamber to the rear. The working chambers at the interior of the torus are made leakless by elastic packing members, which are mounted upon each piston. As a piston approaches an immediately preceding piston, the fuel mixture contained in the working chamber is compressed, which causes suction in the chamber at the rear of the piston.
U.S. Pat. No. 2,349,848 discloses a mechanism that includes an annular chamber having a shaft coaxial with the chamber and rotatable relative thereto. The shaft is coupled to a plurality of double-faced pistons by a plurality of rigidly attached arms. A gear ring, associated with each of the arms, moves adjacent pistons successfully toward and away from one another.
U.S. Pat. No. 2,840,058 discloses an alternating piston-type internal combustion engine that includes two pairs of pistons and three exhaust ports. A fuel-air mixture is fed between the pistons through a port past a valve, when the volume between the pistons is at its maximum. The mixture is then compressed and a spark plug is energized to ignite the  mixture. At the point of explosion, the valve is closed due to pressure buildup and the piston is locked in position by engagement of a cam stop with a pin. The resulting expansion forces the trailing piston forward and pulls the shaft around with it to the final exhaust stroke position, where the space between the pistons is open to the atmosphere through an exhaust port. A pair of lips, which slide over one another, seal the annular recess and, thus, seal the cylinder between the pistons.
U.S. Pat. No. 3,822,971 discloses a rotary piston engine that has a toroidal cylinder having in its sidewall three sets of exhaust ports and intake ports and appropriately positioned spark plugs. The ports and the spark plugs are arranged in one-hundred twenty degree intervals around the cylinder. Two pairs of oppositely positioned double-ended pistons located in the cylinder cover or uncover the ports, with the pistons of each pair being interconnected by rotative radial members. Seals are positioned between the pistons.
U.S. Pat. No. 3,034,486 discloses a pulsating rotary engine that includes six evenly spaced pistons and six evenly spaced trailing pistons arranged in alternating relationship in a toroidal cavity defined between housing segments and rotating respectively with ring gears. In one embodiment, three respective pairs of intake and exhaust ports are provided evenly spaced around the periphery of the housing and circumferentially aligned. The sets of pistons alternately move toward and away from one another as they rotate with the ring gears. Finally, U.S. Pat. No. 3,807,368 discloses a rotary piston machine, whose pistons include curved flanges that allow the pistons to seal the cylinder wall opening at the radial inner side of each combustion chamber.
While the above-described rotary engines are generally functional, they tend to be complex and, as such, relatively expensive to produce. What is needed is a rotary opposed piston engine, whose design generally reduces the number of components, thus, allowing the engine to be manufactured relatively economically.